


Yandere Dadster

by HappyFazzbearPonies2



Category: Undertale (Underfell)
Language: English
Status: In-Progress
Published: 2017-08-01
Updated: 2017-08-02
Packaged: 2018-12-09 17:32:33
Rating: Mature
Warnings: Graphic Depictions Of Violence, Major Character Death
Chapters: 3
Words: 2,022
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11673825
Author URL: https://archiveofourown.org/users/HappyFazzbearPonies2/pseuds/HappyFazzbearPonies2
Summary: Gaster had finally lost it. Years of being inflicted by his sons' abuse and hatred against him put him over the edge. He is so hurt. He just wanted to have his boys love him again. He wanted to have a happy family again...Whatever the cost.





	1. Kidnapping is definitely not illegal, right?

**Author's Note:**

> I have been working on this for a while. And I thought you guys needed SOMETHING while I'm on stale for stories. So here you guys go. I'll stream whatever I have within a week and you guys can read it.
> 
> Until i can get back onto the inspiration train for the Adoption fic.

Gaster’s boys weren’t behaving themselves. They were yelling and swearing and trying to get out of their rooms. They were making such a mess, and Papyrus has already set fire to the wardrobe that was supposed to be filled with clothes on Monday.

 

Sans broke the bedframe and left the mattress untouched. Both of their rooms have black, ashy marks all across the walls and ceiling.

 

But Gaster didn’t get mad.

 

Sans and Papyrus were confused, afraid if Gaster dares say it.

 

When monsters are confused or afraid, they’ll retaliate against the problem, beat it up until they get answers.

 

Gaster will tell them later, when they will listen to their father.

* * *

 

 

Sans has worn himself out yelling, he sat cross-legged on the mattress, fuming as anger and loathing for his captor boiled hotter and hotter inside of him. It’s temperature only rose when he realised he was too tired to let the rest of it out.

 

For once Sans cursed himself for being so goddamn lazy.

 

He leaned back and sprawled on the bed and glared up at the ceiling, he could hear his brother from the other side of the hall, still making a great amount of noise.

 

Sans groaned loudly, digging in his phalanges into his skull. A headache pounded it’s way into its head. He was tired, he wanted sleep, but the noises were too loud. Sans flipped over and curled up against himself and tried to drown out everything, he squeezed his eye-sockets closed.

 

. . .

 

Everything went quiet.

 

Sans sighed in relief and relaxed his eye-sockets, but still kept them closed. The only noises were the quiet hum of the laser beams preventing him an escape and his slowing breathing.

 

He nodded off gently, but his high alertness picked up on gentle footsteps and he quickly sat up.

 

Right outside the room was Gaster, who looked surprisingly calm.

 

A tense moment of silence filled the air until Sans decided to speak up.

 

“Alright,” Sans snarled, “enough is enough. What’s the deal, old man? Why are we here?!”

 

Gaster looked at him silently and a small smile appeared on his face. Sans wanted to punch it off him.

 

“You’re safe, now, Sans. Both of you are.” Gaster tilted his head slightly; his voice strangely soft and unshaken. “I had enough of being such a bad father, avoiding my children for so long. So I’m going to be here for you two, now.”

 

“Well you could have avoided all that if you didn’t betray us in the first place,” snapped Sans.

 

“Oh no, I never meant to hurt you or Papyrus, Sans. I never wanted that to happen.”

 

“Then why did you make us in the first place? Why did you give us a consciousness?!” barked Sans, “We thought you loved us but really you didn't! Some Father you are!”

 

The rage that couldn’t be released broke free and flooded him with new strength and he conjured a large, dragon-like skull that began to fill with a blinding energy. With a roar, Sans let loose the powerful energy at Gaster.

 

A loud explosion of sound made him fly back and hit the wall. Sans slumped down and let out a moan. His eyes were closed.

 

When he slowly opened them, he saw that the beams flared brighter than ever and Gaster’s face didn’t change.

 

Gaster sighed, “I am sorry Sans, I really am. I had made a mistake and you and Papyrus payed the price. But I promise I will make everything better, we’ll be a family again.”

 

“I hate you,” spat Sans, “I want you _dead_.”

 

But Gaster had already left, leaving Sans quite alone.


	2. Undyne sans skeletons

**Summary for the Chapter:**

> Undyne notices that her skeletons aren't around

**Notes for the Chapter:**

> WHELP.

“Papyrus?” Undyne barked at the empty house, “Papyrus!”

 

Undyne kicked opened Papyrus’s bedroom door violently and stormed in. She glared at the uneven, bumpy covers and went to the side of the bed.

 

“You’re missing training, skeleton man! Why are you sleeping so late?” Undyne grabbed the covers and pulled them off the bed, “I had to beat up a dummy while I was waiting for—”

 

Undyne stopped when she realised she was talking to nothing but suspiciously arranged pillows.

 

“What the…” Undyne muttered, eyes flickering in confusion. “Paps?” Undyne opened the wardrobe with significantly less force than the bedroom door.

 

“Papyrus? Sans?”  She walked down the hall and took a peek in Sans’s room.

 

“Sans?” Undyne murmured, expecting the lazy Vice-Captain to be snoring the day away on his bed. But all that lay on it was a ball of sheets and blankets.

 

“ _Mrrreewwwooowww,_ ” purred Waffles, who trotted towards Undyne and brushed against her legs.

 

Undyne screeched in horror and backed away, and ended up falling over the railing. The fish warrior crashed onto the ground floor with a loud grunt.

 

Undyne stood up shakily and swayed before righting herself up.

 

“Goddamn cats,” hissed Undyne, “stupid pets, stupid cats… stupid phobia.”

 

It was obvious that Papyrus nor Sans were in the house. But it was too early for Sans to be bothered to be up and Papyrus always comes over when he wakes up. This sudden change of schedule rubbed her in a very wrong way.

 

This was made even more unnerving when she noticed the two food-bowls for his two pet cats weren’t overflowing with special cat food. Even Bartholomew the Rock was not given a fresh batch of sprinkles.

 

Frowning, she walked around the quiet house, feeling more and more unnerved, right near the door, she saw an large rim of charred plaster and soot encircling the corner between the door and the table. Like someone had come into the skeletons’ house and the two brothers were attacking the intruder with their Blaster. But…

 

Undyne walked over to the blast and trailed her fingers across the circle of soot. There was no sign of dust of a dead monster nor was the shape of one. Unless the enemy was a huge circle blob thing itself then that would explain it. Maybe some rouge Moldybygg? No. There weren’t any slime spots or dust; and the rim was too perfect to be a Moldybygg…

 

Maybe the intruder could use defence magic?  A force field of sorts?

 

But why were they in Pap’s house in the first place? Undyne observed the place more. Besides the circle obviously made by a Blaster, there were no signs of a fight. This fight either ended at the door and the intruder fled or…

 

Undyne stared at Sans’s bedroom door. Sans always kept it locked, why would it be not when she went in?

 

Papyrus came over to train first thing after taking care of his cats and getting ready… but why hasn’t she seen him yet?

 

That’s when Undyne started to think that the intruder won the fight.

 

There was another loud crash as Undyne burst out of the house. She sprinted towards Grillby’s and went storming in. A few of the patrons fell out of their chairs from the vibration of the door hitting the wall.

 

Grillby looked unimaginably bored and stood there while Undyne got up to the bar.

 

“You’re loud, Co-Captain,” said Grillby holding a clean cup in his hands, “you made my patrons fall over and spill their beverages, but they had it coming to them. Do you want anything?”

 

“Has Sans dropped in lately?” asked Undyne, “I want to know when he last popped in here.”

 

Grillby set the cup down and thought for a moment. “You seem pretty concerned about my most regular customer, is everything alright down there at the Royal Headquarters? Aren’t you usually with Paps, beating each other up at this time in the morning?”

 

“That’s  _Captain Papyrus_ , to you,” she snapped.

 

“Oh please,” Grillby rolled his eyes, “that kid is still ‘Paps’ to me ever since he started working here when my father ran this bar. And even if he is one of the most feared monsters in the Underground, I don’t care. Paps will always be Paps.”

 

“How nice,” simpered Undyne before turning her mocking voice into a snarl, “but you haven’t answered my question.”

 

Undyne leaned over the bar, glaring as much as she could at the bright flames that was Grillby,  _“When was the last time Sans dropped in this dingy bar?”_

Grillby sighed with annoyance and adjusted his glasses, “Sans was here yesterday for Lunch. But he didn’t come in for Breakfast or After-Breakfast this morning. Much unlike him. He never misses an opportunity to drop in and eat whatever is on the menu.”

 

“What about Papyrus?” probed Undyne.

 

“Never comes in unless it’s to come pick up his drunk brother. He hates this place, thinks I’m trying to poison my customers with an overdose of grease. I don't do that to anyone who hasn’t asked for it.”

 

Undyne felt something go cold inside of her.

 

Grillby looked at her, “So, you want something or what?”

 

“No, I don’t.” Undyne stiffly straightened up and started to go for the door, stepping on a monster’s hand on the way. The monster yelped and cradled his injured hand and glared at her before crawling back onto his chair as Undyne left the bar.


	3. That's not my skeleton

**Summary for the Chapter:**

> Undyne bumps into Gaster.

**Notes for the Chapter:**

> I know they are short but quality over quantity right?........right?

Continuing her search to find Sans and Papyrus, she trekked across the snowy forest, looking for them until coming at a dead end right at the door to the Ruins. Undyne wouldn’t admit it to anyone, especially to Papyrus, that she was really panicking now.

Speeding her way back to the town of Snowdin to continue her search in Waterfall, she came to a skidding stop just when the skeleton brothers’ house came in sight. Right outside the steps was a tall, thinly built skeleton with a cracked skull and a box of things in his hands.

“Doctor Gaster?”

Gaster turned around and stared at Undyne blankly.

“Oh. Hello, Co-Captain Undyne. What brings you to Snowdin?” asked Gaster, his voice only just about heard by her.

“Better question. Why are  _ you  _ in Snowdin?” Undyne retorted, feeling something crawl down her back.

“Grabbing some Cinnamon Buns and other pastries. Muffet does make nice pastries herself but the price is also. So I came all the way over here,” Gaster smiled slightly.

“Yeah, sure.” Undyne said, not believing a word. She strode up to Gaster, a spear in hand. She was incredibly intimidating even though the skeleton was slightly taller than her.

Usually when monsters sees Undyne coming up to then with a huge spear, they tend to turn tail and run as fast as they can… but not Gaster. Gaster stood there all the while Undyne came close.

“Because clothes are definitely Cinnamon Buns.” She snatched the box away from him and snorted angrily, “Why are you really here? Why are outside Papyrus’s house? Why do you have their stuff?!”

Gaster went completely silent.

_ “Well?” _

Gaster kept his silence before murmuring, “That is none of your concern.”

Undyne let out a mirthless laugh before she could stop herself, “None of my concern? What the hell do you mean by that? Papyrus and Sans just disappeared and I see you outside with their stuff, why wouldn’t it be my concern?”

Something flashed across Gaster’s only functioning eye-socket,  but his expression didn’t change.

“Do you have something to do with this?” said Undyne in a quiet, dangerous voice.

“…….No.”  answered Gaster.

He went to turn around but Undyne grabbed his arm.

“ _ Liar.”  _ Undyne snarled.

Gaster didn’t make eye-contact.

“I should just dust you right here, right now.”

Gaster didn’t respond.

“But you’re the only one who knows, don’t you? So killing you won’t do any good. But once I find my skeletons, you’re gonna  _ pay.  _ You hear me?”

Gaster turned his head just slightly in her direction, “My break is almost over. I should be getting back.”

Gaster shook Undyne’s hand off his arm and started to walk calmly to Waterfall.

Undyne glared at the scientist until he disappeared into the mist. Undyne stared at the box of things on the ground and picked it up.

“I’ll find you guys…” Undyne murmured to the things, but got no answer back. She walked back into the house to put the stuff back into their right places.


End file.
